Well known member of the Kennedy family on trial accused of driving while impaired because of ambient here tonight ABC's Lindsay Janice on the case. On the eve of her trial for drugged driving. Kerry Kennedy's defense attorney William Aaron -- did not wife the daughter of senator Robert F Kennedy is ready to accept a plea deal. Telling ABC news she's sticking to her not guilty plea to driving under the influence of the generic version of sleep aid Ambien. The 54 year old human rights activist was arrested in July 2012. After police say she -- like to tractor trailer with her Lexus -- in New York highway. And kept driving. She was later found slumped over the wheel for SUV. And then I have no memory. Until I was stopped at a traffic light and a police officer was at my car -- Kennedy told police she may have mistakenly taken an Ambien that morning instead of her thyroid medication. The powerful sleep drug carries a warning against taking it then driving. But New York prosecutors are going after her saying that even if she accidentally -- herself she broke still -- if she kept driving after feeling the pills affects. -- -- Forward knocking you out she is responsible for taking the medication that's in her house and making sure that she's taking the right medication. -- Kennedys in court tomorrow her case is raising concerns about people taking the drug incorrectly. The warning label on -- states it should only be taken before -- and David only. When you can get a full night's -- a lot of people watching this Lindsay thank you.

This transcript has been automatically generated and may not be 100% accurate.

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